Television apparatus



Feb. 28, 1939. E, TRAUB 2,149,198

TELEVI S I ON APPARATUS Filed Dec. 16, 1956 ununnmu umuumm Patented Feb.28, 1939 P ArENT OFFICE TELEVISION APPARATUS Ernest Traub, London,England 1 Application December 15, 1936, Serial No.'11 5,904

In Great Britain December 16, 1935 4 Claims. (o1.- 178-113) Thisinvention relates to television apparatus of .the kind employingmechanical scanning. The invention has particular reference to the meansused in such apparatus for obtaining correct phasing of the receivingwith the transmitting apparatus, so as to obtain correct framing of theimage produced at the receiver.

Hitherto it has been the practice to correct the phasing by rotating thestator of the motor 10 which drives the rotating scanning device, thestator winding, or the whole motor carcase being so mounted as to permitsuch rotation. Such rotation of the stator causes slight acceleration ordeceleration of the rotor and thus of the scanlll ning device, so thatthe phasing is adjusted.

This arrangement, however, suffers from practical disadvantages,particularly in systems employing high speed motors. In such cases it isdesirable to bolt the motor down onto a bed of 20 sponge rubber or otherabsorbent material, so

as to reduce noise; it is then difllcult or impossible to arrange forrotation of the stator.

According to the present invention I employ a scanning device of thekind in which scanning 25 is effected by the co-operation of stationaryand rotating members and I so mount the stationary member of this devicethat it can be rotated substantially about the axis of the device.Framing can then be eifected by rotational adjustment of the stationarymember. Examples of scanning devices of the kind referred to aredescribed in the specifications of prior British Letters Patent Nos.394,446, 412,026, 419,120, 425,552, 429,690, 440,055 and 448,738.

35 The invention is illustrated in the accompanying drawing, which is ofa somewhat diagrammatic character. In this drawing Figures 1 and 2 are aside elevation and a plan respectively of a scanning device of the kinddescribed in my 40 prior British specification No. 425,552, but modifiedin accordance with the present invention; Figure 3 is a side elevationof a device of the kind described in my prior British specification No.448,238, similarly modified.

45 The device of Figures 1 and 2 comprises a polygonal drum l, which isrotated about its axis by a motor 2. Each of the side faces of the drumis provided with a reflecting surface, the various reflecting surfaceseach lying at a difierent angle 0 to the axis. Co-operating with thisrotating member is a stationary member 3, comprising a number ofreflecting surfaces each inclined at a difierent angle to the axis.Light from a source 4 passes through a modulating device 5 and a lens 55G and falls on the lower part of one of the reflecting surfaces of therotating member I. From thence'thelight beam is reflected onto thestationary'member 3, thence backonto the upper part of the reflectingsurface of the drum I, and thence through a lens 1 onto the screen 8,where 5. it forms a small spot of light. Rotation of the drum 1 causesthis spot to move in a line transversely across the screen, while thedifierent inclination of the reflecting surfaces of the stationary androtating mirrors cause successive scanning lines to be displacedvertically on the screen.

In accordance with the present invention, the stationary member 3 is somounted that it can be rotated about the axis of the drum I. As shown,the member 3 is supported by brackets 9 upon a 1 toothed ring l0,rotatably mounted upon the upper end of the motor 2. This ring isengaged by a worm II which can be rotated by means of a knob 12. Framingof the picture can be accomplished by rotating the knob l2 and thusadjust- 0 ing the stationary member 3 about the axis of the device. Amovement of the stationary member through a distance equal to the widthof one of its component reflecting surfaces is suflicient to shift thepicture laterally through its whole width.

In the device of Figure 3 scanning in the two dimensions of the pictureis efiected by two separate devices, each of the kind above referred to.The high speed or line scanner is in general similar to the scanningdevice of Figures 1 and 2, but the reflecting surfaces of the rotatingdrum 2| and of the stationary member 23 are all parallel to the axis ofthe device. The beam of light leaving this device is directed by areflecting sur- 36 face 30 into the low speed or framing scanner, whichcomprises a drum 3|, rotated by a motor 32 and having its side facesformed with reflecting surfaces, and a stationary member 33 having aplurality of reflecting surfaces, all the refleeting surfaces lyingparallel to the axis. The stationary member 33 is supported by brackets39 on a toothed wheel 40 engaging with a worm 4|, which can be rotatedby a knob 42. The low speed and high speed scanners are thus similar toone another, but are mounted with their axes perpendicular and havetheir drums driven at different speeds. The beam of light leaving thelow speed scanner passes through the lens 1 onto 50 the screen 8. Withthis arrangement transverse framing of the picture can be effected byrotation of the knob 12, while vertical framing can be effectedindependently by adjustment of the knob 42. I 4 I i What I claim anddesire to secure by Letters Patent is:

A television scanning device comprising a rotating member, a stationarymember disposed concentrically about said rotating member, a refleetingsurface on said rotating member adapted to receive a beam of light fromsaid stationary member and direct it onto the area to be scanned, andmeans for adjusting said stationary member about a point correspondingsubstantially to the axis of the device.

2. A television scanning device comprising a rotating member ofpolygonal section, a stationary member disposed concentrically aboutsaid polygonal member, a plurality of stationary mirrors carried by saidstationary member, a plurality of rotating mirrors each carried by oneface of said rotating member, and means for adjusting said stationarymember about an axis which substantially coincides with the axis of saidrotating member.

3. A television scanning device comprising a rotating member and astationary member disposed concentrically about said rotating member,said rotating and stationary members together constituting a high speedor line scanner, a second rotating member and a second stationary memberdisposed concentrically about said second rotating member, said secondrotating and stationary members together constituting a low speedframing scanner, all of said members being adapted to receive insuccession a modulated beam of light and impart scanning movementthereto, means for effecting adjustment of said first stationary membersubstantially about the axis of said first rotating member andindependent means for effecting adjustment of said sec ond stationarymember substantially about the axis of said second rotating member.

4. A television scanning device comprising a rotary member, a stationarymember disposed concentrically about said rotary member, said stationarymember comprising a plurality of stationary reflectors each adapted toreceive a beam of light from said rotary member and to direct it backthereonto, and means for adjusting said stationary member about an axiswhich substantially coincides with the axis of said rotary member.

ERNEST TRAUB.

